I just did a send of emails as usual, and the recipient said he didn't get it, but then checked the spam filter and found it was flagged as spam due to "INVALID_MSGID (Message ID is not Valid according to RFC 2822)". The message ID was:
Message-ID: <{4E488B79-6A8B-43C6-B540-A0453A48E845}>
Which looking at RFC 2822 seems to have the problem with the curly braces, and doesn't have the second part after the @.
Can I suggest that this be modified to be more compliant? Perhaps have the second half (often used as the machine name) as an optional text, but default to "finalbuilder". Thus it would become:
Message-ID: <4E488B79-6A8B-43C6-B540-A0453A48E845@finalbuilder>
Thanks!
Matthew